Study Evaluating Dexketoprofen Trometamol/Tramadol Hydrochloride Analgesic Efficacy in Acute Low Back Pain

Inclusion Criteria:

1. Properly executed written informed consent.

2. Male or female patients aged 18 years to 65 years.

3. Patients with acute low back reporting pain of at least moderate intensity atScreening (NRS score ≥ 5). The onset of the current acute low back pain episode iswithin 48 hours prior to Screening.

4. Patients with or without radiculopathy will be included, excluding those withneurological signs, according to the Quebec Task Force classification.

5. Naïve patients to any low back pain or patients with previous history of low backpain experiencing a new episode, preceded by a period of at least 2 months withoutany low back pain prior to Screening.

6. Patients free from analgesic (as per exclusion criterion 14) due to previouslyadministered pain killer (immediate or slow release formulations), according tophysician's judgment.

7. Females participating in the study must be either:

• Females of non childbearing potential, defined as any woman who had undergonesurgical sterilization (documented hysterectomy, bilateral salpingectomy, orbilateral oophorectomy) or is more than 2 years post menopausal (defined as nomenses for 12 months);

• Females of childbearing potential (following menarche until menopause unlesspermanently sterile) provided that they have a negative pregnancy test atScreening and are routinely using an effective method of birth controlresulting in a low failure rate (ie, combined hormonal contraception,intrauterine device, condoms in combination with a spermicidal cream, malepartner sterilization (vasectomy), bilateral tubal occlusion or total sexualabstinence) during the study treatment.

8. Mentally competent and able to understand and give written informed consent prior toScreening.

9. Compliant to undergo all visits and procedures scheduled in the Study.

Exclusion Criteria:

1. Patients who are judged by the Investigator not to be suitable candidates for thestudy treatments and the Rescue Medication (RM) based on their medical history,physical examination, Concomitant Medication (CM) and concurrent systemic diseases.

2. Clinically significant abnormalities in the vital signs as per Investigator'sjudgment.

3. Patients with acute low back pain and radiation to limb with presence of neurologicsigns (focal weakness, asymmetry of reflexes, sensory loss in a dermatome, or lossof bowel, bladder, or sexual function) according to Quebec Task ForceClassification.

4. History of hypersensitivity to the study treatments, RM or to any other nonsteroidalanti-inflammatory drugs (NSAIDs), or opioids.

5. Known photoallergic or phototoxic reactions during treatment with ketoprofen orfibrates.

6. History of peptic ulcer, gastrointestinal disorders when taking NSAIDs,gastrointestinal bleeding, or other active bleeding.

7. History of allergy (eg, precipitate attacks of asthma, bronchospasm, acute rhinitis,or cause nasal polyps, urticaria or angioneurotic oedema) to the study treatments,RM or to any other NSAIDs, or opioids.

8. Anamnestic mild to severe renal dysfunction, mild to severe hepatic dysfunction, asper Investigator's judgment.

9. Patients with chronic dyspepsia.

10. Patients with severe heart failure [Class III and Class IV of New York HeartAssociation (NYHA) Classification].

11. History of hemorrhagic diathesis and other coagulation disorders.

12. History of or current epilepsy or convulsions.

13. Patients with Crohn's disease or ulcerative colitis.

14. Patients receiving monoamine oxidase (MAO) inhibitors (a minimum of 14 days ofwashout must elapse prior to the Screening).

15. Treatment with topical preparations/medications within 4 hours prior to Screening,anesthetics and muscle relaxants within 8 hours prior to Screening, short-actinganalgesics (eg, paracetamol) within 4 hours prior to Screening, other analgesicswithin 5 half-lives prior to Screening or use of an opioid within the 14 dayspreceding Screening.

16. Treatment with high doses of salicylates (≥3 g/day), anticoagulants, thrombolyticand antiplatelet agents, heparins, corticosteroids (except inhalers and topicalagents), lithium methotrexate, used at high doses of 15 mg/week or more, hydantoins (including phenytoin) and sulphonamides, antiepileptics, antipsychotics, serotoninreuptake inhibitors and tricyclic antidepressants, and analgesics within 48 hours or 5 half-lives (whichever is the longer) prior to Screening.

17. Patients using sedatives (eg, benzodiazepines) and hypnotic agents within 8 hoursbefore Screening.

18. Any chronic or acute painful condition other than the study indication that mayinterfere with the assessment of the efficacy of the study treatment.

19. Any non-pharmacological interventional therapy for low back pain (physical therapy,acupuncture, massage etc.) one month before Screening.

20. Patients with litigation related to work.

21. Patients with severe dehydration (caused by vomiting, diarrhea, or insufficientfluid intake) within one month prior to Screening.

22. Severe respiratory depression according to physician's judgment.

23. Participation in other clinical studies in the previous 4 weeks.

24. History of drug or alcohol abuse. For the purpose of the study, alcohol abuse isdefined as regularly intake of more than 4 units of alcohol per day (1 unitcorresponds approximately to 125 ml wine, 200 ml beer, 25 ml spirit).

25. History of any illness or condition that, in the opinion of the Investigator mightpose a risk to the patient or confound the efficacy and safety results of the study.

26. Pregnant and breastfeeding women: a pregnancy test will be performed on all women ofchildbearing potential at Screening.

27. Patients presenting any of the contraindications reported fordexketoprofen/tramadol, tramadol or paracetamol (according to the SmPC).

28. Known or suspected serious spinal pathology (eg, metastatic, inflammatory orinfective diseases of the spine, cauda equine syndrome, trauma, spinal fracture).

29. Spinal surgery within the preceding 6 months.